You can use excel but i need mathematical formulas to solve myself with handwritten. Please share formulas and explain.

The Country Transportation Deparment needs to determine usage factors by day of the week for a popular toll bridge connecting different parts of the city. In the current study, they are considering only working days. Suppose that the number of car using the bridge each working day over the past four weeks (in thousands of cars): Find the seasonal factors corresponding to daily usage of the bridge